Loss of Performance. Daily wear and tear and oils from your skin can breakdown silicone, plastic and rubber making CPAP masks less efficient over time.
Discoloration. If your CPAP equipment turns yellow or cloudy, it is time to replace them. Those are obvious signs of usage that cannot be washed away.
Odour. If it smells, it must go! Even if you clean them regularly, CPAP parts can hide mould and mildew putting you at risk of breathing in bacteria and pathogens when you sleep.
Irritated Skin. There are number of reasons why you may break out in a rash or have irritated skin; sometimes your mask might be too tight. But a buildup of facial oils on your CPAP mask could cause irritation too.